Mental health diagnoses are common in pediatric practice. Abundant evidence demonstrates that many medications used to treat children with mental health conditions are prescribed in circumstances or combinations for which they are not recommended. Such use may lead to patient harms such as onset of diabetes or suicidal ideation, and potentially avoidable emergency department visits and hospitalizations. This project proposes (1) to describe in detail the epidemiology of patient safety in ambulatory care settings, focusing on medication safety in children with mental health diagnoses who are enrolled in New York State Medicaid ; (2) to assess the extent to which three strategies: a) receipt of primary care in a National Committee for Quality Assurance (NCQA)-recognized patient-centered medical home (PCMH); b) a new state policy (carve-in) that assigns responsibility to manage the prescription pharmaceutical insurance benefit to managed care plans rather than the state Medicaid program; and c) a more patient-centered, comprehensive set of medication reconciliation (med rec) practices can reduce potentially dangerous medication use or undesirable consequences / patient harms in this populations; and (3) to assess whether or not a state Department of Health quality department's implementation of a survey to assess medication reconciliation in practices throughout Medicaid is an effective way to enhance the performance of such practices. The epidemiological study will use cross sectional, univariate, bivariate, and multivariable analyses for each year from 2014 to 2017, including logistic regression and regression risk analysis. It will look at clinical, patient, contextual, and practice characteristics that are associated with lower and higher uses of potentially dangerous medication practices and undesirable outcomes. It will describe identified disparities, considering characteristics such as gender, race/ethnicity, rural/urban residence, foster care status, and level of poverty in the home county. A propensity score analysis will help to assess the association of the specified medication practices with undesirable outcomes and patient harm. Assessment of the PCMH and med rec strategies will utilize propensity score analyses that are modified from the models developed during the epidemiological analysis. The state carve-in policy, implemented in late 2011, will be assessed using a segmented regression analysis of an interrupted time series from 2008 to 2016.=Medication reconciliation practice will be assessed using a survey instrument developed by an AHRQ- CMS CHIPRA Center of Excellence in the federal Pediatric Quality Measures Program. The impact of measurement on med rec practices will be assessed using a cluster randomized trial with a stepped wedge design, surveying one third of practices in all years, on third in years two and three and one thir in year three only. This project promises to provide more detailed insight both into an important patient safety risk in ambulatory settings for a vulnerable population and also into how well several strategies reduce risk in real world settings.